1. Field
Exemplary embodiments of the present invention relate to semiconductor fabrication technology, and more particularly, to a method for fabricating a metal pattern in a semiconductor device.
2. Description of the Related Art
As highly integrated, semiconductor devices have fine patterns. As a result, a photoresist layer used in forming fine patterns has almost reached a limit of its resolution. Accordingly, a fine pattern formation method using a spacer pattern technology (SPT) process has been introduced.
Meanwhile, a metal pattern is applied to increase an operation speed of a device. In particular, when a metal pattern is formed of tungsten, fluorine-based gas is used as tungsten etching gas. In this case, a side surface damage of a hard mask nitride layer over a tungsten layer may occur. Furthermore, if the etching is continuously performed using the damaged hard mask nitride layer, the tungsten layer may be cut in the middle. On the other hand, when polymer-based gas is used in consideration of the side surface damage of the hard mask nitride layer, a less-etching may occur. That is, the tungsten layer is not completely etched, and a pattern is not formed. In order to prevent an occurrence of the less-etching and compensate for a low etching speed when using polymer-based gas, the height of a mask over the hard mask nitride layer may be increased. In this case, when the height of the mask is increased to a certain value or more, lifting may occur due to the nature of the SPT process.
FIG. 1 is a transmission electron microscopy (TEM) photography illustrating the features of the conventional semiconductor device.
Referring to FIG. 1, a tungsten layer was cut due to a side surface damage, and a less-etching occurred. As described above, when a less-etching occurs, a lower layer may be not completely etched, and a desired pattern may be not formed.